Memory management methods and systems for page-out mechanism are provided. A page-out mechanism is performed via an OS (Operating System) based on a parameter of the page-out mechanism, wherein the page-out mechanism moves data from a memory to a storage unit. A usage of a page-out partition in the storage unit is monitored. The parameter of the page-out mechanism is dynamically set according to the usage of the page-out partition, wherein when the usage is increased, the parameter of the page-out mechanism is decreased, and when the usage is decreased, the parameter of the page-out mechanism is increased.